Question: If $a + b + c = -3$ and $x + y + z = -1$, what is $8b - 7x + 8c + 8a - 7y - 7z$ ?
Solution: $= 8a + 8b + 8c - 7x - 7y - 7z$ $= (8) \cdot (a + b + c) + (-7) \cdot (x + y + z)$ $= (8) \cdot (-3) + (-7) \cdot (-1)$ $= -24 + 7$ $= -17$